These are ok for a temp fix, but long term the screws dont realy bite enough, infact they normaly dig in and can split the strains apart, meaning separated single strands will start to burn out, if you do use one of these, your better off making up a small circular pressure plate (from an old piece of copper pipe or something), mount the the small plate between the screws and the cable, so the screws compress the plate directly onto the stranded cable.

I agree, Zirk. Even soldering the strands doesn't work, for much the same reason; the screws push the solder away over time and the connection loosens, bringing you back to square one. A bloody great crimping tool is the only answer!